This invention relates generally to mortise locks for use in doors, and more particularly to a mortise lock having a deadbolt which automatically projects when the door is closed.
A mortise lock is designed to fit into a mortised recess formed in the edge of a door which is opposite to the edge of the door that is hinged to the door frame. The mortise lock generally includes a rectangular housing, or case, which encloses the lock components. One of the lock components includes a deadbolt which projects beyond the edge of the door and into an opening or strike plate in the door frame to lock the door in a closed position. The deadbolt is moveable to a retracted position inside the case to permit opening of the door by operation of a latch operator, such as a doorknob or lever handle.
Mortise locks are available which utilize deadbolts which project automatically upon closing of the door. Mortise locks with automatic deadbolts are often used in hotel room doors so that hotel guests do not need to independently and manually throw the deadbolts after closing their hotel room door.
Mortise lock assemblies with automatic deadbolts generally comprise a deadbolt biasing mechanism in the housing of the mortise lock assembly for continually biasing the deadbolt outwardly to the extended position. A stop mechanism within the housing holds the deadbolt in a retracted position against the force of the biasing mechanism when the door is opened. A trigger mechanism is provided for sensing the strike plate or door frame when the door is closed. The deadbolt trigger mechanism functions to release the deadbolt stop mechanism so that the deadbolt projects to the extended position into an opening in the strike plate or door frame for locking the door. The deadbolt trigger mechanism is usually associated with an auxiliary latch which is pivotally mounted in the housing for movement from an extended position beyond the edge of the door to a retracted position in the housing when the auxiliary latch engages the strike plate or door frame. When the latch operator is used to retract the deadbolt for unlocking and opening the door, the deadbolt stop mechanism reengages the deadbolt for holding the deadbolt in the retracted position.
Automatic deadbolt mortise lock assemblies often have problems with retaining the deadbolt in the retracted position. Inadvertent release of the deadbolt causes the deadbolt to project to the extended position before the door is closed. In addition, automatic deadbolt mortise lock assemblies sometimes require excessive force to manually retract the deadbolt or high door closing force to release the deadbolt stop mechanism. The high force requirements can result in overstressing and breakage of the deadbolt and deadbolt biasing mechanism.
For the foregoing reasons, there is a need for a mortise lock utilizing an automatic deadbolt which does not require excessive force to retract the deadbolt or to release the deadbolt stop mechanism upon door closing. The new mortise lock should also safely retain the deadbolt in the mortise lock assembly when the door is opened and prevent accidental projection of the deadbolt. The new mortise lock assembly should also be straightforward to manufacture and use.
Therefore, it is an object of the present invention is to provide a mortise lock including an automatic deadbolt which can be easily retracted using a door knob or lever handle.
Still another object of the present invention is to provide a mortise lock including an automatic deadbolt which requires only normal door closing force for triggering deadbolt projection.
A further object of the present invention is to provide a mortise lock including an automatic deadbolt which does not accidentally project when the door is open.
According to the present invention, an automatic deadbolt mechanism is provided for a mortise lock of the type comprising a housing for accommodating the lock components including the deadbolt projecting mechanism, a deadbolt mounted in the housing for movement relative to the housing between a retracted and extended position, means for continuously biasing the deadbolt to the extended position, and means for moving the deadbolt to the retracted position of the deadbolt. The automatic deadbolt projecting mechanism for use in the mortise lock comprises a blocking element adapted to be pivotally mounted in the housing for movement relative to the housing. The blocking element has a first position where a blocking surface is adapted to engage the deadbolt for holding the deadbolt in the retracted position against the force of the deadbolt biasing means and a second position where the blocking surface does not engage the deadbolt. Means are provided for pivoting the blocking element to the second position. The blocking element pivoting means includes a sensor adapted to be mounted in the housing for movement relative to the housing between an extended position and a retracted position. The blocking element pivoting means is operative to pivot the blocking element to the second position when the sensor is in the retracted position. The sensor is adapted to contact the strike plate upon closing of the door for movement to the retracted position so that the deadbolt automatically moves to the extended position under the force of the deadbolt biasing means when the door is closed.
Also according to the present invention, a mortise lock is provided for mounting in a free edge of a door, the mortise lock comprising a housing, a deadbolt mounted in the housing for movement relative to the housing between a retracted position and an extended position, means for continuously biasing the deadbolt to the extended position and means for moving the deadbolt from the extended position to the retracted position of the deadbolt. A blocking element mounted in the housing for pivotal movement relative to the housing is biased to a first position where a blocking surface on the blocking element engages the deadbolt for holding the deadbolt in the retracted position against the force of the deadbolt biasing means and a second position where the blocking surface does not engage the deadbolt. Means are provided for pivoting the blocking element to the second position against the force of a blocking element biasing means. The blocking element pivoting means includes a sensor mounted in the housing for movement relative to the housing between an extended position and a retracted position where the sensor is inside of the housing. The blocking element pivoting means is operative to pivot the blocking element to the second position when the sensor is in the retracted position. The sensor is adapted to contact the strike plate upon closing of the door for movement to the retracted position so that the deadbolt automatically moves to the extended position under the force of the deadbolt biasing means when the door is closed.
An important feature of the present invention is the blocking element arrangement which is easily pivoted to the non-blocking position by the camming, pivotal action of the blocking element pivoting means. The latter includes a pivoting trigger hammer mounted in the housing adjacent the sensor for engagement and movement by the sensor when the sensor is moved to the retracted position. A pivoting release lever is mounted in the housing between the trigger hammer and the blocking element. The release lever is engaged for movement by the trigger hammer when the trigger hammer is pivoted by the sensor. The release lever cams the blocking element when the release lever is rotated for moving the blocking element to the second position. The result is an automatic deadbolt mechanism which requires minimal force upon door closing to trigger projection and to subsequently retract the deadbolt using the latch operator.
Additional objects, features and advantages of the present invention will be apparent from the following description in which references are made to the accompanying drawings.